Soil Formation, Composition, and Degradation
What is Soil?
In environmental science, soil is the interface between the geosphere, atmosphere, and biosphere. Soil science studies soil, particularly focusing on soil as a resource for conservation and rational exploitation.
Soil Formation
Soil formation, or pedogenesis, occurs in three stages (not specified as ‘Stage C, STAGE AND STAGE AC ABC’ in the original text, which seems incorrect. Stages are typically described differently, e.g., initial, juvenile, mature, etc., but without further context, I will leave it as a general statement):
Soil formation happens in 3 stages.
Factors Involved in Pedogenesis
- The Nature of the Bedrock: The bedrock provides most of the soil’s mineral components and influences the early stages of its formation. The rock type influences soil texture.
- Weathering: Immature or young soils have not had time to fully develop, while mature soils are stable and well-developed.
- Topography: Soils on slopes are generally less developed than those on flat plains, where mature soils are more common.
- Climate: This is the most important factor. Generally, different rocks under the same climate produce similar soils.
- Living Things: Organic matter enriches the soil, favors chemical weathering processes, protects the soil from erosion, mixes soil materials, and participates in aeration.
- Human Activities: Humans impact soil in multiple ways, almost always negatively. Massive deforestation, fires, pollution, agricultural and livestock overexploitation, and urbanization are some harmful practices for soil health. However, humans can also positively influence soil through fertilization, planting trees, building terraces, etc.
Soil Composition
Soil is composed of a wide variety of inorganic and organic materials.
Inorganic Materials
- Inherited Minerals: Their composition is the same as that of the bedrock.
- Altered Minerals: These have a different composition than the parent rock due to chemical weathering. Clays are the most abundant.
Organic Materials
These consist of the remains of living organisms, leading to what is called humus or mulch. There are two types of humus:
- Raw or Young Humus: Consists of organic remains that are little or not at all decomposed.
- Developed Humus: Black in color and acidic. Clays combine with humus to form organomineral or humic-clay complexes, which are very important for soil fertility because they retain water and ions.
Soil Degradation
Soil degradation occurs when soil loses its vegetation cover and becomes vulnerable to external geological agents. These agents cause severe erosion, leading to the loss of materials, especially organic matter and fine particles.
Factors influencing soil erosion include:
- Climate: Torrential rains have high erosive capacity.
- Relief: Slopes exceeding 15% are easily erodible.
- Vegetation: A dense plant cover mitigates erosion.
- Nature of the Terrain: Impermeable terrains promote runoff.
Desertification
Desertification is a process of physical, chemical, and biological soil degradation, rendering it incapable of sustaining productive vegetation. Spain is the European country where desertification is the most significant environmental problem. Almost one-third of Spain’s total area is at high or very high risk of desertification.